Sea Shepherd campaigners set off for Antarctic waters on Wednesday, saying they expected increased aggression from the Japanese fleet after their harassment tactics kept the cull to a record low last season.

The hunt netted just 103 minke whales, less than half its tally the previous year, and no fin whales, with Japanese authorities blaming "unforgivable sabotage" by activists.

High-seas clashes between the groups are common and Sea Shepherd - which has sent three ships to the Antarctic this year - regularly pelts the whaling ships with stink bombs, attempts to foul their propellers and manoeuvres vessels between harpoons and whales.